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<div>Are you using Diablo or Trunk?</div>
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If you're using trunk the default scheduler is MultiScheduler, which uses Chance scheduler. I think Diablo uses Chance by default?
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<div>--scheduler_driver<br>
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<div>Unless you've explicitly selected the LeastCostScheduler (which only exists in Diablo now) I wouldn't worry about those settings.</div>
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<div>Did you explicitly define a scheduler to use?</div>
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<div id="divRpF26150" style="direction: ltr; "><font face="Tahoma" size="2" color="#000000"><b>From:</b> openstack-bounces+sandy.walsh=rackspace.com@lists.launchpad.net [openstack-bounces+sandy.walsh=rackspace.com@lists.launchpad.net] on behalf of Jorge Luiz
Correa [correajl@gmail.com]<br>
<b>Sent:</b> Thursday, November 10, 2011 6:27 AM<br>
<b>To:</b> openstack@lists.launchpad.net<br>
<b>Subject:</b> Re: [Openstack] Four compute-node, everytime the 1st and 2nd are choosen<br>
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<div>Is there a flag in nova.conf that permits we configure that? In documentation we can see that exists some algorithms used by scheduler. But, I don't know how to choose that one best fit our requirements. </div>
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<div>Thanks!</div>
<div>:)<br>
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<div class="gmail_quote">On Wed, Nov 9, 2011 at 1:36 PM, Ed Leafe <span dir="ltr">
<<a href="mailto:ed.leafe@rackspace.com" target="_blank">ed.leafe@rackspace.com</a>></span> wrote:<br>
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On Nov 9, 2011, at 7:51 AM, Razique Mahroua wrote:<br>
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> I use the default scheduler, in fact, I've never tunned it really.<br>
> The hypervisors all run KVM<br>
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This is where the flag is defined in <a href="http://nova.scheduler.least_cost.py" target="_blank">
nova.scheduler.least_cost.py</a>:<br>
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32 FLAGS = flags.FLAGS<br>
33 flags.DEFINE_list('least_cost_functions',<br>
34 ['nova.scheduler.least_cost.compute_fill_first_cost_fn'],<br>
35 'Which cost functions the LeastCostScheduler should use.')<br>
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Since the default weighting function is 'compute_fill_first_cost_fn', which, as its name suggests, chooses hosts so as to fill up one host as much as possible before selecting another, the pattern you're seeing is expected. If you change that flag to
'nova.scheduler.noop_cost_fn', you should see the hosts selected randomly. The idea is that you can create your own weighting functions that will select potential hosts in a way that best fits your needs.<br>
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-- Ed Leafe<br>
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-- <br>
- MSc. Correa, J.L.<br>
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